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From b87edf043bc03527ac702d1fdc678e930f77a082 Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Mon, 6 Sep 2021 19:55:08 -0700
Subject: [PATCH] Add portable fallbacks for __builtin_clz[ll]
---
softfp.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/softfp.c b/softfp.c
index 2a1aad0..801ecc3 100644
--- a/softfp.c
+++ b/softfp.c
@@ -35,7 +35,25 @@ static inline int clz32(uint32_t a)
if (a == 0) {
r = 32;
} else {
+#ifdef __GNUC__
r = __builtin_clz(a);
+#else
+ int t;
+
+ t = ((a & 0xffff0000) == 0) << 4;
+ a >>= 16 - t;
+ r = t;
+ t = ((a & 0xff00) == 0) << 3;
+ a >>= 8 - t;
+ r |= t;
+ t = ((a & 0xf0) == 0) << 2;
+ a >>= 4 - t;
+ r |= t;
+ t = ((a & 0xc) == 0) << 1;
+ a >>= 2 - t;
+ r |= t;
+ r += 2 - a & -((a & 2) == 0);
+#endif
}
return r;
}
@@ -47,7 +65,15 @@ static inline int clz64(uint64_t a)
r = 64;
} else
{
+#ifdef __GNUC__
r = __builtin_clzll(a);
+#else
+ int t;
+
+ t = ((a & 0xffffffff00000000) == 0) << 8;
+ a >>= 32 - t;
+ r = t | clz32(a);
+#endif
}
return r;
}
--
2.32.0
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